1. Field of the Invention
The present invention relates to an image reading apparatus for reading radiation image information recorded on a stimulable phosphor sheet stored in a cassette, and thereafter erasing remaining radiation image information from the stimulable phosphor sheet.
2. Description of the Related Art
There has heretofore been known a stimulable phosphor which, when exposed to applied radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet radiation, or the like), stores part of the energy of the radiation, and, when subsequently exposed to applied stimulating rays such as visible light, emits light in proportion to the stored energy of the radiation. An image forming apparatus, which is known in the art, records radiation image information of a subject such as a human body on a stimulable phosphor sheet having a stimulable phosphor layer formed thereon.
An image reading apparatus has a cassette loader for loading therein a cassette holding a stimulable phosphor sheet, which has radiation image information of a subject such as a human body recorded thereon, a reader for applying stimulating light to the stimulable phosphor sheet to read the recorded radiation image information from the stimulable phosphor sheet, and an eraser for applying erasing light to the stimulable phosphor sheet after the recorded radiation image information has been read, thereby erasing any remaining radiation image information from the stimulable phosphor sheet. After the remaining radiation image information has been erased from the stimulable phosphor sheet, the stimulable phosphor sheet is returned into the cassette and unloaded from the image reading apparatus for reuse.
The stimulable phosphor sheet used in the image reading apparatus may develop a curl at its leading end, due to certain temperatures at which it is used, e.g., at low temperatures during winter and in cold climates. If the stimulable phosphor sheet is curled at its leading end, then the curled end cannot enter smoothly between feed rollers while the stimulable phosphor sheet is being transported through the image reading apparatus, resulting in a failure to efficiently read the recorded radiation image information from the stimulable phosphor sheet in the image reading apparatus.
For using the image reading apparatus in environments having low temperatures, such as during the winter and in cold climates, the room in which the image reading apparatus is installed needs to be heated quickly by a heater. When the room is heated, moisture condensation may occur in the image reading apparatus, due to a temperature difference that is abruptly caused between the temperature in the room and the temperature within the image reading apparatus.
Japanese Laid-Open Patent Publication No. 05-262012 discloses a recording apparatus with a heating mechanism for heating a thermosensitive recording medium to a predetermined temperature. The recording apparatus has a first heater, a cooler, and a second heater, which are disposed along a feed path for feeding the thermosensitive recording medium. The thermosensitive recording medium is heated to a predetermined temperature by the first heater and then cooled by the cooler. Thereafter, the thermosensitive recording medium is heated to a predetermined temperature by the second heater for writing information thereon.
In Japanese Laid-Open Patent Publication No. 2003-287866, the applicant of the present application has proposed a drying apparatus for drying an image recording medium for use in a printer processor. The drying apparatus has a plurality of nozzles disposed over a feed path for feeding the image recording medium and held in communication with an air duct. Drying air, which is heated by a heater disposed in the air duct, is delivered through the air duct by an air blower, and applied through the nozzles to the image recording medium, thereby drying an image recording medium that has been washed with water.
The recording apparatus disclosed in Japanese Laid-Open Patent Publication No. 05-262012 serves to achieve a stable printing quality by heating the thermosensitive recording medium before writing information thereon. The drying apparatus proposed in Japanese Laid-Open Patent Publication No. 2003-287866 serves to apply drying air to dry the image recording medium, which becomes wet after it is washed with water. Therefore, these apparatus belong to a different technical field, which differs from the art of heating an image reading apparatus used in low temperature environments.
The apparatus disclosed in Japanese Laid-Open Patent Publication No. 05-262012 and Japanese Laid-Open Patent Publication No. 2003-287866 are unable to prevent moisture condensation due to a rapid temperature rise caused by heating when the image reading apparatus is used at low temperatures during winter and in cold climates, and such apparatus are also unable to eliminate curling that may possibly occur at the end of a stimulable phosphor sheet that is fed into the image reading apparatus.
According to one solution, a dehumidifier, for example, may be incorporated in the image reading apparatus, for removing moisture condensation from the image reading apparatus. However, this solution is disadvantageous in that the image reading apparatus is increased in size due to the dehumidifier.
When the leading end of the stimulable phosphor sheet becomes curled, then the curled end prevents the stimulable phosphor sheet from entering smoothly between the feed rollers as it travels through the image reading apparatus. As a result, the recorded radiation image information cannot be read efficiently from the stimulable phosphor sheet by the image reading apparatus.